All three projects of the proposed program involve the study of the consequences of loss-of-function mutations generated by targeting of genes encoding tumor suppressors in mice. These studies require expert and efficient pathological analyses of large number of specimens (embryos, tissues and tumors), to investigate phenotypic manifestations affect normal murine development and/or contributing to tumorigenesis. The diagnostic procedures that are central to the development of the program include macroscopic anatomic examination, microscopic histology, in situ hybridization and immunohistochemistry. The aim of this Core facility is to provide murine pathology serve by an experienced pathologist combining uniquely in his background expertise in both human clinical pathology and mouse development and pathology, including oncogenesis. Quality control in the Core will be secured by optimizing, standardizing nd streamlining the procedures involved, to [provide interpretations rapidly and efficiently. Active interactions with the program participants are anticipated and should enhanced the development of the projects involving mouse models.